“… The key concern, the Israelis said, is where the jihadis go after Assad falls. Do they stay on in Syria to fight any Alawite militias that may appear? Do they go west to Lebanon, to fight the Shiite group Hezbollah? South to try to cross into the Golan, and fight the Israeli army? Or east into Iraq, to fight as Sunnis against the Shiite-led government of Prime Minister Maliki — which the Israelis saw as perhaps the most likely outcome?

But there is another possible outcome: that the jihadis go to Europe to commit acts of violence and terror there. Why would hundreds of them possibly go to Europe? Because they came from Europe. The facts are pretty clear: There are hundreds and hundreds of European Muslims now fighting in Syria. When I met recently in Washington with the top civil servant in one of Europe’s foreign ministries, this was his greatest fear: What will they do when they come “home,” their fighting skills now honed through months of combat alongside other jihadis from Libya, Pakistan, Afghanistan, Iraq, and many other countries?

The French believe there are dozens of French Muslim jihadis in Syria. Kern quotes Dutch public broadcasting reporting that “the Netherlands has become one of the major European suppliers of Islamic jihadists” and about 100 Dutch Muslims are fighting in Syria. The Belgians think there are at least 70 Belgian Muslims there, and a Belgian newspaper called the country the top supplier of youth going to Syria for jihad.

There is a growing recognition in Europe of the danger around the corner. Already two Danish Muslims have been killed as part of the rebel forces in Syria, and the March 25 edition of a leading Danish newspaper carried a story headlined “Youthful gang members are going to war in the name of Islam.” The story continued:

According to the Danish Secret Services . . . several members of the most violent gangs of immigrants in Copenhagen are currently in Syria where they have gone in order to participate in jihad… These people are already potentially dangerous and when they return home, they have access to arms and explosives. It is very worrisome to see these types of ties forming between Islam and criminals,” says the head of the Danish Secret Services.

… I can see why the Israelis worry where the jihadis will turn once Assad is gone, but at least Israel has a border with Syria it can keep closed and fight to protect. The counter-terror forces in Europe will not be able to prevent these jihadis from crossing Europe’s borders, for they all hold passports. Trouble ahead.